Added Cell level control for Table Borders (#1285)

Author: Kaustbh

CHANGELOG.md

@@ -18,6 +18,7 @@ This can also be enabled programmatically with `warnings.simplefilter('default',
 
 ## [2.8.2] - Not released yet
 ### Added
+* new optional parameter `border` for table cells [issue #1192](https://github.com/py-pdf/fpdf2/issues/1192) users can define specific borders (left, right, top, bottom) for individual cells
 * [`FPDF.write_html()`](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.write_html): now parses `<title>` tags to set the [document title](https://py-pdf.github.io/fpdf2/fpdf/fpdf.html#fpdf.fpdf.FPDF.set_title). By default, it is added as PDF metadata, but not rendered in the document body. However, this can be enabled by passing `render_title_tag=True` to `FPDF.write_html()`.
 * support for LZWDecode compression [issue #1271](https://github.com/py-pdf/fpdf2/issues/1271)
 ### Fixed

docs/Tables.md

@@ -38,6 +38,7 @@ Result:
 * control over borders: color, width & where they are drawn
 * handle splitting a table over page breaks, with headings repeated
 * control over cell background color
+* control over cell borders
 * control table width & position
 * control over text alignment in cells, globally or per row
 * allow to embed images in cells
@@ -277,6 +278,68 @@ Result:
 All the possible layout values are described
 there: [`TableBordersLayout`](https://py-pdf.github.io/fpdf2/fpdf/enums.html#fpdf.enums.TableBordersLayout).
 
+## Set cell borders
+
+_New in [:octicons-tag-24: 2.8.2](https://github.com/py-pdf/fpdf2/blob/master/CHANGELOG.md)_
+
+```python
+from fpdf import FPDF
+
+pdf = FPDF()
+pdf.add_page()
+pdf.set_font("Times", size=16)
+with pdf.table() as table:
+    for data_row in TABLE_DATA:
+        row = table.row()
+        for datum in data_row:
+            row.cell(datum, border="LEFT")
+pdf.output('table.pdf')
+```
+
+Result:
+
+![](table_with_cell_border_left.jpg)
+
+```python
+from fpdf import FPDF
+
+pdf = FPDF()
+pdf.add_page()
+pdf.set_font("Times", size=16)
+with pdf.table() as table:
+    for data_row in TABLE_DATA:
+        row = table.row()
+        for datum in data_row:
+            row.cell(datum, border="TOP")
+pdf.output('table.pdf')
+```
+
+Result:
+
+![](table_with_cell_border_top.jpg)
+
+```python
+from fpdf import FPDF
+from fpdf.enums import CellBordersLayout
+
+pdf = FPDF()
+pdf.add_page()
+pdf.set_font("Times", size=16)
+with pdf.table() as table:
+    for data_row in TABLE_DATA:
+        row = table.row()
+        for datum in data_row:
+            row.cell(datum, border=CellBordersLayout.TOP | CellBordersLayout.LEFT)
+pdf.output('table.pdf')
+```
+
+Result:
+
+![](table_with_cell_border_left_top.jpg)
+
+All the possible borders values are described there: [`CellBordersLayout`](https://py-pdf.github.io/fpdf2/fpdf/enums.html#fpdf.enums.CellBordersLayout).
+
+
 ## Insert images
 
 ```python

docs/table_with_cell_border_left.jpg

@@ -310,6 +310,74 @@ class TableBordersLayout(CoerciveEnum):
     "Draw only the top horizontal border, below the headings"
 
 
+class CellBordersLayout(CoerciveIntFlag):
+    """Defines how to render cell borders in table
+
+    The integer value of `border` determines which borders are applied. Below are some common examples:
+
+    - border=1 (LEFT): Only the left border is enabled.
+    - border=3 (LEFT | RIGHT): Both the left and right borders are enabled.
+    - border=5 (LEFT | TOP): The left and top borders are enabled.
+    - border=12 (TOP | BOTTOM): The top and bottom borders are enabled.
+    - border=15 (ALL): All borders (left, right, top, bottom) are enabled.
+    - border=16 (INHERIT): Inherit the border settings from the parent element.
+
+    Using `border=3` will combine LEFT and RIGHT borders, as it represents the
+    bitwise OR of `LEFT (1)` and `RIGHT (2)`.
+    """
+
+    NONE = 0
+    "Draw no border on any side of cell"
+
+    LEFT = 1
+    "Draw border on the left side of the cell"
+
+    RIGHT = 2
+    "Draw border on the right side of the cell"
+
+    TOP = 4
+    "Draw border on the top side of the cell"
+
+    BOTTOM = 8
+    "Draw border on the bottom side of the cell"
+
+    ALL = LEFT | RIGHT | TOP | BOTTOM
+    "Draw border on all side of the cell"
+
+    INHERIT = 16
+    "Inherits the border layout from the table borders layout"
+
+    @classmethod
+    def coerce(cls, value):
+        if isinstance(value, int) and value > 16:
+            raise ValueError("INHERIT cannot be combined with other values")
+        return super().coerce(value)
+
+    def __and__(self, value):
+        value = super().__and__(value)
+        if value > 16:
+            raise ValueError("INHERIT cannot be combined with other values")
+        return value
+
+    def __or__(self, value):
+        value = super().__or__(value)
+        if value > 16:
+            raise ValueError("INHERIT cannot be combined with other values")
+        return value
+
+    def __str__(self):
+        border_str = []
+        if self & CellBordersLayout.LEFT:
+            border_str.append("L")
+        if self & CellBordersLayout.RIGHT:
+            border_str.append("R")
+        if self & CellBordersLayout.TOP:
+            border_str.append("T")
+        if self & CellBordersLayout.BOTTOM:
+            border_str.append("B")
+        return "".join(border_str) if border_str else "NONE"
+
+
 class TableCellFillMode(CoerciveEnum):
     "Defines which table cells to fill"
 

docs/table_with_cell_border_left_top.jpg

@@ -11,6 +11,7 @@
     WrapMode,
     VAlign,
     TableSpan,
+    CellBordersLayout,
 )
 from .errors import FPDFException
 from .fonts import CORE_FONTS, FontFace
@@ -251,13 +252,18 @@ def render(self):
         self._fpdf.l_margin = prev_l_margin
         self._fpdf.x = self._fpdf.l_margin
 
+    # pylint: disable=too-many-return-statements
     def get_cell_border(self, i, j, cell):
         """
         Defines which cell borders should be drawn.
         Returns a string containing some or all of the letters L/R/T/B,
         to be passed to `fpdf.FPDF.multi_cell()`.
         Can be overriden to customize this logic
         """
+
+        if cell.border != CellBordersLayout.INHERIT:
+            return str(cell.border)
+
         if self._borders_layout == TableBordersLayout.ALL:
             return 1
         if self._borders_layout == TableBordersLayout.NONE:
@@ -770,6 +776,7 @@ def cell(
         rowspan=1,
         padding=None,
         link=None,
+        border=CellBordersLayout.INHERIT,
     ):
         """
         Adds a cell to the row.
@@ -788,6 +795,7 @@ def cell(
             rowspan (int): optional number of rows this cell should span.
             padding (tuple): optional padding (left, top, right, bottom) for the cell.
             link (str, int): optional link, either an URL or an integer returned by `FPDF.add_link`, defining an internal link to a page
+            border (fpdf.enums.CellBordersLayout): optional cell borders, defaults to `CellBordersLayout.INHERIT`
 
         """
         if text and img:
@@ -819,6 +827,7 @@ def cell(
             rowspan,
             padding,
             link,
+            CellBordersLayout.coerce(border),
         )
         self.cells.append(cell)
         return cell
@@ -838,6 +847,7 @@ class Cell:
         "rowspan",
         "padding",
         "link",
+        "border",
     )
     text: str
     align: Optional[Union[str, Align]]
@@ -849,6 +859,7 @@ class Cell:
     rowspan: int
     padding: Optional[Union[int, tuple, type(None)]]
     link: Optional[Union[str, int]]
+    border: Optional[CellBordersLayout]
 
     def write(self, text, align=None):
         raise NotImplementedError("Not implemented yet")